Mounting for sprockets, pinions, or the like



Feb. 9, 1954 M. T. SCHUMB 2,668,454

MOUNTING FOR SPROCKETS, PINIONS OR THE LIKE Filed Oct. 22, 1952 "w ill W Patented Feb. 9, 1954 Lou-Iran srA'rEs PATENT o e-Flee MOUNTING F OR SPROCKETS, PINIONS,

OR THE LIKE Martin T. Schumb, Milton, Mass., assignor to :Boston Gear WorksDivision The -Murray :Gompany; of Texas, Inc., North Quincy, Mass., acorporation of Delaware "Application October :22, 1952, Serial No. 316,143

a diameter considerably largerthan though the toothed elementwere to be'mounteddirectly on the shaft. Thus, 'if-'the'toothedelement have a small'number of teeth, that is to-sayabout twenty -or--less,-the material intervening between the roots of the teethand the wallof the-bore of the toothed element may =beof a thickness approximating-the minimum thickness permissible towithstand the stresses of use, so that-weakening said wall, for example," by-boring holes or forming deep keyways or slots therein" cannot bepermitted. It is with reference to such' toothedelements, having a-sma1l *numberof teethandwhich are to be -mounted'in use-upon asplit bushing that the present invention particularly relates.

It" has heretoforebeen-"proposed toemploy a tapered bushing for -'-de-mountab1y securing a large gear or sprocket to ashaft and, in such a "construction; to provide the bushing-and sprocket -01" gearwith bolt-receiving holes formed partly 'inthe'bushing and partly in the hub portion of the sprocket or" gear. -Such-anarrangement is "very useful when the sprocket orgear is of such a diameter-as to have sufficient material between its axial boreand the-rootsof the teeth to permit formation of the bolt holes without unduly weakening the sprocket or "gear; but for de mountably securing a" sprocket or :gear' having a small" num- =ber'of-teeth:and, wherein the axial-bore is of a diameter "such that there is little material between the ,wall'of'the bore and the roots of the teeth, 'such' aprocedure isjnot permissible since the formation of bolt-holes in the hub portion of :the sprocket or gear would'unduly. weaken it.

.Ithas also been proposed .to attach a wheel to a shaftby: the use of a tapered bushing having a radial flange, with provisionfor bolting it to the .,hub of the wheel .and' this might perhaps be an effective way .of ldeemountably'attaching a sprocketz-or, gear of large diametertojits shaft; that is to say asprocket or gear-wherein theroot diameter of "its teeth sufiiciently large tOT'DlOVide an' adequate-thickness ,of"materia1 between the "rootsof the teeth and the-wall of the axial bore toreceive, bolts for-attaching the *hubportion of the sprocket or gear to the bushing flanga but this method again would not -be-app1icable:=to a sprocket or pinion having few teeth. The present invention contemplates the use of a flanged split bushing, such as "just above' referred to,

which is designed to be connected by bolts: to a complementary flange integral with but axially spaced from the sprocket-or pinion. Theemployment of such a-sprocket or pinion-with an integral attaching flange has not heretofore been regardedas practical because, in order'to provide roomfor the boltsand to insure proper strength of the parts, the diameters '-ofthe complemental flanges will usually=exceed -the root diameter of the teeth of the sprocket =orpinion and, sincethe attaching flange, integral-with the sprocket or pinion, spaced from the-sprocket or pinion but a short distance to-conserve space, for example in a sprocket merely enough to-provide clearance for a sprocket-chain, it is impossible to form the teeth=ofthesprocket or-pinion by the use of rotary cutters; which is thecustomary way of cutting spur teeth-in pinions or sprockets. This difficulty doubtless account-s for the fact that as respects pinions-or sprockets of small diameter (that is to say having but few teeth) -the use of complemental radial'flanges asa-mode-of securing the pinion or sprocket to-a split-bushing or pinion may be effectively but de-mountably attached to a shaft without necessitating the provision of bolt-receiving holes,- recesses or'keyways in the bore of the sprocket -or pinion. A further object is to provide a tooth unit comprising a hub, a toothedflangeand an attaching -flange, a-ll;1integrally uni-ted, thefiangesbeingaxially spaced a distance not substantiallyexceeding the thickness of either flange, wherein the attaching flange of said unit is of an outside diameter ,.exceeding the root diameter of the teeth or even exceeding the outside diameter of the toothed element. A further object to providea novel method of making a toothed unit comprising a tooth flange and an attaching flange of substantially the same diameter and spaced aparta distance not. substantially exceeding the thicknesscf the attaching; flange, whereby properly shaped spurteeth may be formed on the tooth ,fiange without'damage to the untoothediflange.

One embodiment of the invention is illustrated in the accompanying drawings and pointed out more particularly in the following more detailed description:

Fig. 1 is a front end elevation of a toothed element with its associated bushin in accordance with the present invention;

Fig. 2 is a side elevation of the parts shown in Fig. 1;

Fig. 3 is a rear end elevation of the toothed element of the present invention, the bushing being omitted;

Fig. 4 is a section substantially on the line 44 of Fig. 3;

Fig. 5 is a side elevation of the bushing showing the radial split at one side of the latter;

Fig. 6 is a rear end elevation of the bushing of Fig. 5;

Fig. 7 is a diagram illustrating a method of making the teeth of the sprocket or pinion;

Fig. 3 is a fragmentary edge elevation of one of the teeth of the sprocket or pinion illustrating the tool marks resultant from the method of making the sprocket or pinion; and

Figs. 9 and 10 are fragmentary, radial sections through the assembled toothed element and bushing illustrating respectively the way of drawing the parts toward each other and of separating them from each other.

Referring to the drawings the numeral 1 designates a shaft carrying the mounting 2 of the present invention. As here illustrated the mounting comprises a tooth unit, which includes a toothed flange, here shown as constituting a sprocket, although it is to be understood that the invention is equally useful whether the toothed flange be a sprocket or pinion and when it is referred to as a sprocket it is to be understoodthat it is so designated merely for convenience in description and that the term sprocket is intended to be broadly inclusive of any toothed element having radial teeth, in-

cluding a spur pinion or gear.

The unit 3 (Fig. 4), which includes the sprocket. comprises the hub portion 4 having at its opposite ends the integral radial tooth flange 5 and attaching flange 6 respectively. The hub 4 is provided with an axial bore 1 which tapers in diameter, being smallest at the end at which the toothed flange B is located and increasing in diameter toward its opposite end. A sprocket or pinion (having a small number of teeth, that is less than about twenty) which is to be mounted on a bushing, must have a bore so large, relatively to the tip diameter of the teeth that but little metal intervenes between the roots of the teeth and the wall of the bore. For example, the maximum thickness of metal at the roots of the teeth may well be less than the root-to-tip height of a tooth. Because of the thinness of the wall of the bore, it is undesirable to form holes, recesses or slots therein, and in accordance with the present invention, the wall is preferably smooth and uninterrupted throughout. The flange 5 is shaped, as hereinafter more fully described, to provide the radial or spur teeth 8, the

root portions of these teeth being indicated by the character R. The attaching flange 6 is untoothed, its peripheral surface being smoothly cylindrical. As indicated in Fig. 3, the flange 6 is provided with internally screw threaded holes 9 and I 9, here shown as located on the same diameter of the flange. While two such holes are here shown it is contemplated that more holes maS be provided, but it is desirable in any event hat h holes be located symmetrically about the circumference of the flange. As illustrated, the diameter of the untoothed flange 6 approximates the diameter of the circle defined by the outer ends of the teeth 8. This is for the very practical purpose of providing a suflicient body of material to sustain the stresses of use. The diameter of the flange B is thus substantially greater than the diameter of the root circle of the teeth.

For securing the tooth unit 3 on the shaft I there is provided a bushing device ll (Fig. 5) comprising the radial flange l2 and the elongate barrel or sleeve portion IS, the latter being tapered with substantially the same taper as the bore 1 in the part 3, and the flange l2 being of substantially the same outside diameter a the flange 6 of the part 3. The bushing ll, including both its flange l2 and its barrel or sleeve portion [3, is longitudinally split, as shown at M, and normally has a gap at the location of the split so that the bushing is capable of contracting in diameter. As shown in Fig. 6, the bushing is provided with an axially extending keyway 15 on the same diameter as the split H but at the opposite side of the bushing, to facilitate securing the bushing to the shaft so that it cannot rotate on the shaft. 7

The flange l2 of the bushing is provided; at diametrically opposite points, with unthreaded holes l6 and I! which are preferably countersunk, as shown at I8 and I9 (Fig. 5), at the outside face of the flange. The axes of these holes 16 and I! are aligned with the axes of the holes 9 and [0 when the bushing i assembled with the unit 4. When thus assembled, bolts 22 pass through the holes I6 and I1 into the holes 9 and I0, respectively, having screw-threaded engagement with the latter holes. By tightening these bolts the flange [2 may be drawn forcibly toward the flange 6, thu causing the tapering barrel or sleeve I3 to seat very snugly within the bor I of the unit 3. When the bolts are fully tightened the heads of the bolts will be seated in the countersinks l8 and 19.

The flange I2 is also provided with holes 20 and 2i which are internally screw threaded, but the flange 6 is not provided with any holes corresponding to or normally opposite to the holes 20 and 2 l By withdrawing the bolts 22 from the holes 9 and I0 and screwing them into the holes 20 and 24, the ends of the bolts may be caused to engage the outer or right-hand face of the flange 6 and thus to force apart the flanges l2 and 6. The steps of drawing the flanges l 2 and 6 together and of forcing them apart respectively are diagrammatically indicated in Figs. 9 and 10.

With this arrangement it is thus possible readily to substitute one tooth unit for another, assumin that each tooth unit thu employed will have an axial bore 1 of the same diameter and taper, and holes 9 and ID in the same locations.

As may be noted by reference to Fig. 4, the flanges 5 and 6 of the unit 3 are spaced apart a distance D, which does not substantially exceed the thickness of either flange. Devices of this type are commonly used in places where it is necessary to be as economical of space as possible or where it is impossible to use a hub of more than a very definitely limited axial length. When the toothed flange is a sprocket, the space D will usually not exceed that necessary to provide clearance for the links of the sprocket chain engaging the teeth of the sprocket. Thus it is evident that the opposed faces of the flanges 5 and 6 will be close together, ordinarily not ta e-m 5 ,7 further. apartthan. thehepthnione of-othe teeth havipg .aniintegral, .radial.x flan e .twhichhis op b1 .1 the toothed .element. .'.Since (the .,clearance Posed :to'Lthe-oouter iiace or .fthejflange -of said spaceJDI' isl thus small, 'it issnot possibletof form azuniteandmeansfor moving saidfflanges toward standard teeth on"theflange5 by methods most or'from each other. rcommonlysused in shapingspurgearlteeith since 1/5 In mbinn ion, a hub Tha'vin inte r l the usual rotarycutters employed'forthat purpose 'iilanges .atfits .oppos'iteends, one of the (flanges would cut into the "flange"- 6. '"In accordance-with thawin r dial te h I and th h r being ,i the present invention, has '.diaggrammaticalty toothed; theoutside'fldiameter' of the latterflange "illustrated.inl'Fig.i'7, the teethi8 .arejiormed in e n f hei rootidiameten of the: teeth of the ,the part5,1 for example by mountingithejfiange ifi st'fl h lth ffi -n s inge'spaced apart axiall 6 t on. a, rigid. support W,' f or linstance the table 7 aldistaincemot. substantially, exceeding the depth of a suitable lmachineltoolihaving .a cutter"T 01'- the. teeth, 'thehuh.having atapered axial :bore whichreciprocates vertically. Byothe nseiofta iWTh W ill istsm hw nd ci ellmfer h i lly m- 1- toolofappropriate contourl the teethj8 .arethus *intemlpted,itheldie-meter Of. the here-being Such formed the troke of t tt c t at 1 thati'themetal; interveningebetween the: wallet it does.not contact.. the upper .surface .of the the e nd-the robtslf the-teethdoesflnot 811bsflangei'fi. IZ'Ihe teethfthusformed maybeidenti- S n e .1y-exced'inl'thiekness 'thelroot -tor-lt ;fiedj..by the. facttthatoltheynshowi to'ol marks; in height-Gila tooth,-a tap r ngfi in iwith- Lthe nature oft-fine parallel scratches exteriding in thethereih'ithel il hc fih g a axiallybf thetoothedelement,tori-example as2 fl n i d ht ri heuuntoothed-.flan eofthe ..in'dicated.at M .(FigLB). ohllbatan'dtmeansoperative .to .-.move theelaltter 1 By. this procedure in. forming the teeth. itLbefl n e from ea h he comes, possible. tov make lagunittcomprising .the 4-1111 leembinatieh, h ving Ltapered partsand-G i twhieh t h b 4, wit which axialobore.havingsaesmooth wall circumferenthe toothed element 5 is integral, is provided with-2 really =uninte rupted a Jan inte i r dia a'radial flange-6i of a sdiameter*equalling'hor' exflange at .eachtend oneaof. said. radialhfianges ceeding thesrootvdiameteroof the toothed eleb inet 'oth d e fl il p e e hd t ment, and availablefor association with a radial nether fl n esbeingiiuntoothedy th A fla h flangeon a tapered bushing whereby the hub ing y paced fl vn t1511b- 1 gfithe: t t it yxb am ted stantially .-exceeding .that, necessary i to ,..provide a shaft in such a way that it is firmly secured l am Jena epro ett ain a n th to the shaft in a very simple and effective way teeth 6f the Sprocket, t oot diameter of and as easily removed from the shaft when it is the teeth of the p o being S han he desired to do so.. outer diameter of the untoothed flange and the While ne desirable emb di nt of th i axial bore in the sprocket being of such diamevention has herein been illustrated by w y of ter that the metal intervening between the wall xam l it i t b nd t d th t t i of the bore and the roots of the teeth does not tion is broadly inclusive of any and all modifisubstantially exceed in thickness the root-tocations falling within the scope of the appended p height of a teeth, a p ed bushing fittin lai within the axial bore of the hub, said bushing I lai being split in a. diametrical plane at one side 1. In combination with a tapered, split bushd at its pp Side, in the Same plane, ing designed to be fixed to a shaft, a unit comhaving an axi y eXtending y y, a flange 0n prising two coaxial, radial flanges spaced apart the-bushing externally to the hub and confronting and integrally joined to the opposite ends of a 5 the untoothed flange of the latter, and means hub, said flanges being spaced apart a distance for moving the latter flanges toward and from not substantially exceeding the axial thickness each other.

of either flange, one of said flanges being In Combination, a ub hav ng a tapered toothed to constitute a sprocket or pinion, the x al bore Whose wall is smooth and circumunit having a tapered axial bore whose smaller 5 ferentially u nt rr p d a d an t ral, radial end is adjacent to the toothed flange and whose flange at each end, one of Sa d radial flanges bein diameter, at its smaller end, is such that the toothed t0 e-enstitllte a p t a d the other thickness of the metal intervening between the flange being untoothed, e diameter o the axial roots of the teeth and the wall of the bore does bore exceeding One-half the met diameter of the not substantially exceed the root-to-tip height teeth 9 e Sprocket, e flanges being axially of a tooth, the bushing fitting within the axial paced to pr d clearance for a sp k t chain bore of said unit and having an integral raengaging the eeth o t Sprocket, the t didial flange which is opposed to the outer face ameter of the teeth of the sprocket being less of the untoothed flange of said unit, and means, than the 11te1 diamete1 0f the untoothed fl comprising a plurality of independent bolts, for a tapered hu fitting Within the axial bore of moving said latter flanges toward or from each the hub, Said bushmg e p i a iametrical other. plane at one side and, at its opposite side in the 2. In combination with a tapered split bush- Same p ne, having an axially extending keyway, ing designed to be fixed to a Shaft, a unit a flange on the bushing externally to the hub and prising a toothed element having a tapered 5 con-frontmg the um'OPthed flange latter, axial bore which, at its smaller end, exceeds the flange of the bushmg havmg theremapluml' one-half the root diameter of the teeth of the ity 0f symmetrically arranged axially extending toothed element, an untoothed radial flange and unthrea'ded t and the untoothedfiange of a hub, each integral with the toothed element, the hub havmg correspondingly arranged the flange being spaced axially from the toothed threaded holes, bolts normally p g throu element a distance not substantially exceeding the holes in the bush ng flange a d having the axial thickness of the toothed element, said threaded engagement w th the holes in the unaxial bore extending through the toothed eletoothed hub flange r drawing the bushing ment, the hub and the flange, the bushing fitflange toward the untoothed flange 0f th h ting within the axial bore of said unit and the bushing flange having other symmetrically arranged threaded holes for alternative engagement by the aforesaid bolts whereby the bushing flange may be forced away from the unthreaded flange of the hub.

6. In combination, a hub having a tapered axial bore whose wall throughout its entire length is smooth and circumferentially uninterrupted, the hub having an integral radial flange at each end, that one of said radial flanges which is adjacent to the smaller end of the bore being toothed, the diameter of the bore at its smaller end being such that the metal intervening between the wall of the bore and the roots of the teeth does not substantially exceed the root-to tip height of a tooth, the flanges being spaced apart axially a distance not substantially exceeding the depth of said teeth, the toothed flange not exceeding the other flange in radius by more than the depth of a tooth, a tapered bushing fitting within the axial bore of the hub, said bushing being split in a radial plane at one side, the

. bushing flange having two sets of axially extending holes, the holes of one set being unthreaded and those of the other set being threaded, the untoothed flange of the hub having threaded holes arranged to receive bolts passing through the unthreaded holes of the bushing flange whereby the bushing flange and untoothed flange of the hub may be drawn toward each other, the bolts being alternatively engageable with the threaded holes in the bushing flange whereby, by ad- 8 vancing the bolts into contact with the outer face of the untoothed flange of the hub, the bushing flange may be forced away from said latter hub flange. V

7. In combination, a hub having a tapered axial bore and integral radial flanges at its opposite ends, one of the flanges having spur teeth, the other radial flange being untoothed, said flanges being spaced apart a distance not substantially exceeding the depth of the teeth, the external diameter of the untoothed flange exceeding the root diameter of the teeth of the toothed flange, the axial bore, at its smaller end, at least, being of a diameter such that the metal intervening between the wall of the bore and the roots of the teeth does not substantially exceed in radial thickness the root-to-tip height of a tooth, a tapered bushing fitting Within the bore in the hub, the bushing being split at one side in a radial plane and having a radial flange adjacent to the untoothed flange of the hub, and means operative to move the bushing flange toward or from the untoothed flange of the hub. MARTIN T. SCHUMB.

References Cited in the file of this patent UNITED STATES PATENTS Number 

